Nikon CFi 4x Plan Achromat on Canon 100mm f/2.8L Macro IS

Just bought that first macro lens? Post here to get helpful feedback and answers to any questions you might have.

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Carmen
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Nikon CFi 4x Plan Achromat on Canon 100mm f/2.8L Macro IS

Post by Carmen »

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In this thread I report my first impressions of the Nikon CFi 4x Plan Achromat microscope objective MRL00042 mounted on Canon EF 100mm f/2.8L Macro IS USM lens, imaging to a small ASP-C sensor, and of Canon EOS utility.

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The RAF Camera M25x0.75 to M67x0.75 thread adapter places the micro' objective close to macro lens Surface -aprox' 2mm as far as I can tell. In this position, the image quality appeared less than uniform from center to corners as observed through the live view screen. A slim U.V. filter was place between the micro' objective and macro lens, and image quality appeared slightly more uniform to corners.

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600 grit sand paper test on a kitchen counter base. The camera was fixed to the bottom of a small tripod. Vertical alignment of camera to subject base was acheived by centering the observed reflection of lens in live view screen through a small mirror placed flat on improvised base. The sand paper was pulled taught and taped to a flat pasta dough scraper, which was placed on improvised base. Be aware that the sand paper's surface is not perfectly flat.

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At this low 2x magnification, the tripod was stable enough to manually focus the image. The position of the micro' objective remains constant as macro lens focuses internally. The magnification appears to remain constant, throughout focusing range. Macro lens diafragm at f2.8. Resulting photo of sand paper test below, hand focused, 5sec exp' with continuous lighting.

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Then to give some idea of range of focus provided by macro's internal focus mechanism, 3 small coins were arranged on the sand paper to form steps. This optical train allowed to focus through the full 3 coin steps, aprox' 3.9mm, with even more range available. The photo below is a from a P-max stack of just 4 focus slices, 5sec exp' each with continuous lighting, manually focused at each step surface through the camera's live view screen.
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Inspired by this initial success, I attemped more precise focus control vía canon's EOS utility software on my humble windows based note book computer. With same kit as above, I captured some 62 focus slices, at intervals of one mouse click on the >> buton in utility's GUI, 2sec exp' with continuous lighting. Focus stacking process P-max with zerene stacker program. The subject is a tiny beetle I had in my specimen cemetary: Diabrotica speciosa I think. Unfortunately, the poor specimen was so dry that the antenna fell off during manipulation. The brown spots on its back appears more orange when alive.

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I attempted one more "stacked" photo' of a tiny flower, but failed due to camera battery drain before completing desire range of focus. It would seem that focusing vía EOS utility is taxing, consuming considerable battery and computer resources. If one procedes too quickly, the utility freezes. Maybe someone could suggest something, or experiment and report.

Initial impressions and opinion: Given a 100mm macro lens, tripod, and a camera with small ASP-C sensor, the Nikon CFi 4x Plan Achromat presents the amateur macro photographer with a relatively inexpensive entry into low magnification photomicrography. I noticed some vignetting with this optical train. But relatively speaking, it provides an overall flat clean image, and a generous working distance. Additionally, this kit is compact, and allows filters.

The EOS utility is certainly more precise than manuallly focusing by the lens barril. But the process becomes increasingly tedious - not to mention interruptions, distractions, etc... In short, the greater the number of focus slices, the more attractive an automated precise focus system seems to me.

In retrospect, ¿What could have been done differently to improve these the initial results? Given the tripod, base and continuous lighting, I suspect some camera tremor is present in images. An electronic flash would probably improve the images. The heavy porcelanato floor tiles would probably have provided a more stable base than the kitchen counter. And I plan to vary separation distance between the micro' objective and macro lens with spacer rings from inexpensive filters, with the aim of locating an optimum position. ¿Does anything else occurr to you that I may have overlooked? Please tell!

Questions, comments, critiques or concerns are welcome!
Last edited by Carmen on Tue May 19, 2015 2:38 pm, edited 5 times in total.

rjlittlefield
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Post by rjlittlefield »

Carmen, thank you for the test report.

Commenting as I re-read it...

This optical setup should not be expected to give uniform sharpness from corner to corner. The specification "OFN22" means that the objective is rated to give a good image over a 22 mm diameter image, at rated magnification. But using the 100 mm rear lens, you're only operating at 2X, not 4X, so the 22 mm rated circle becomes only an 11 mm circle. That's then an 11 mm circle versus 28 mm diagonal on your APS-C sensor.

It's interesting that adding the slim U.V. filter improved the image quality in corners. I would have expected that to go the other way, but it depends on details of the lens designs that are never known so you just have to test.

I see that you have removed the outer barrel of the objective. That's a good thing to do, but I suspect it's not having the same large effect with this objective that it does with the CFI BE. On the CFI BE, removing the outer barrel significantly improves image quality by removing a partial obstruction in the corners. But your CFI objective has a different design, and it looks like removing the outer barrel may have little or no effect on what light reaches the lens.

Then, in your test image I see a color shift toward magenta in the center of the image and green toward the outside. This is probably a matter of longitudinal chromatic aberration typical of these objectives, combined with some curvature of either the optical field or the subject. Essentially you're a bit one side of focus in the center of the image, and a bit the other side in the corners. The color cast is caused by light spreading unevenly from bright areas into dark areas, green spreading more on one side of focus and red+blue (=magenta) on the other side. In many cases this effect will be greatly reduced by focus stacking, but (especially) with shiny metal subjects you can expect color casts in some areas even with focus stacking.

Regarding automation of your setup, one thing you can do is to either augment or replace Canon EOS Utility to do the control.

To augment it, you can use a keyboard/mouse recorder to capture the sequence of button presses necessary to take a picture and advance the focus, then "play back" that sequence many times to shoot the stack. Examples include http://www.asoftech.com/autome/ and http://www.robot-soft.com/. One person reported to me that I got the robot-soft option ($20) and it couldn't have been simpler to use. Does exactly what you expect. “Train” it to click the EOS change focus >> option X times and then take the image, wait Y seconds and repeat Z times. As I’m taking 25-50 images say 10-15 times per flower I’m shooting, the time savings is huge.

To replace it, consider something like qDslrDashboard (http://dslrdashboard.info/downloads/). That's a cross-platform application that offers some level of control for both Canon and Nikon cameras on seemingly every type of computer and tablet currently sold, with the exception of Mac devices running iOS. I haven't tried it on Windows (which I presume is what you're using), but it works OK for me on an Android tablet once I figured out how to press the right buttons in qDslrDashboard.

Based on the images you're showing here, I'm not worried about vibration. Of course more protection is always better than less, but unless you see some problems by zooming in to 100% pixels at camera resolution, there are probably more important aspects to spend your time on.

--Rik

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Post by Carmen »

Hi Rik!
Again, thank you for your thoughtful comments and suggestions. Regarding color aberrations, it's not so noticeable, and can be corrected. I suspect the Nikon CFi 10x Plan Achromat microscope objective MRL00102 may have less chromatic aberration.

Thank you for the suggestion of automating the use of Canon's EOS utility for capture of focus slices! :) I am investigating this means. But in the long term, I prefer a stack shot or something similar.

I plan to vary the position of micro' objective in relation to 100mm macro lens. This will take some time, but expect to have a better idea of optimum position in the near future. I noticed that in your original tests, you used an adapter + step ring adapter, possibly placing the micro' objective some 6mm from macro lens surface???

In summary, the new kit meets my expectations. It's more a question of fine tuning its use, collecting beautiful specimens, etc...

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Post by rjlittlefield »

Carmen wrote:I noticed that in your original tests, you used an adapter + step ring adapter, possibly placing the micro' objective some 6mm from macro lens surface???
If you're referring to HERE, then the extra ring was only to keep that added aluminum plate from possibly touching the lens surface.

When placing objectives in front of ordinary camera lenses, my standard approach is to place them as close as possible to minimize vignetting issues. A reasonable expectation is this should also minimize optical distortions, because it uses more central parts of the rear lens optics and would match better with that lens's normal mode of operation. I recall that some of your lens tests came out different from that expectation. I would be interested to hear more about that and to see the images so that I could understand better.

The situation is different when placing objectives in front of a reversed Raynox. In that case placing the objective some distance away from the Raynox corresponds more closely to the way the Raynox was designed to be used, and experimentally I do see a small improvement in quality by providing some separation.

--Rik

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Post by pontop »

Thanks for this report.
For automating the proces of taking a stack with internal focusing lenses I might consider Magic Lantern. There is a function that allows you to set endpint, step size (in terms of number of steps of the focusing motor) and number of frames. Then just start it and it will do all the work for you.

Bo

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Post by rjlittlefield »

Good point about Magic Lantern. That also has the advantage that it's self-contained so it can be used in the field with no added parts. I find the user interface to be painfully non-intuitive, so I wrote up a tutorial specifically on how to use it for focus stacking. See HERE for that.

--Rik

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Post by pontop »

User friendlyness is not the number one priority at Magic Lantern. I doubt it is on the priority list at all :wink:

Bo

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Post by Carmen »

pontop wrote:Thanks for this report.
For automating the proces of taking a stack with internal focusing lenses I might consider Magic Lantern. There is a function that allows you to set endpint, step size (in terms of number of steps of the focusing motor) and number of frames. Then just start it and it will do all the work for you.
Bo
much obliged Bo! will investigate. I suspect one of the factors is my humble equipment -note-book computer, etc. Basically experiencing success, and at same time, the limitation of equipment and methods are better known. The way I see this is that every attempt is an opportunity to learn something in the best experimentalist tradition.

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Post by Carmen »

Regarding the distance between 100mm macro lens and nikon CFi 4x plan achromat microscope objective:

I had planned to wait for the spacer ring and/or another filter to test various distances between the two. BUT on the weekend, I finally had the time available to configure kit for a stacked photo' of a fly.

So I FIRST took advantage to attempt a more rigourous RE-TEST of optical train, with and without the UV slim filter between macro lens and micro' objective. I confess the initial test was hurried. The UV Slim filter measures aprox 3.3mm by our humble digital caliper.

Below are mobile telephone photo's, to show how kit is configured and aligned. Be aware the perpendicular alignment is approximate: my best estimate is plus or minus one degree margin of error. in hopes of less vibration, everything was placed on heavy tile floor, close to a structural column.

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In order to avoid posible error or bias, the EOS Utility was used to automatically focus on center of frame in each photo'. Mixed continuous lighting, mostly flourescent, 5 second exposure, macro lens diafragm open to f2.8.

below is WITH UV FILTER
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below is WITH UV FILTER upper right quadrant
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below is WITHOUT UV FILTER
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below is WITHOUT UV FILTER upper right quadrant
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No post processing or edition of test photo's -except to resize image in order to comply with photo' posting requirements.

Questions, comments, and considered opinions are welcome!

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Post by ChrisR »

After lining the quadrant photos up, I see lower contrast and more loss of sharpness further from the corners in the image where the filter was used. The contrast can be "put back" but then some colours start to appear. Purple fringes show more strongly in the "no filter" image, but that may just be because they're better defined.

Towards the middle the sharpness is OK, so I think if the filter were needed then there wouldn't be much lost, there.

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Post by rjlittlefield »

Just checking... Did you have the 100 mm set on or very near to infinity focus? Using an infinity objective, if the rear lens is set far from infinity, things can get weird. I am a little concerned about things being differently weird in the two different cases, due to focusing issues.

--Rik

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Post by Carmen »

ChrisR wrote:After lining the quadrant photos up, I see lower contrast and more loss of sharpness further from the corners in the image where the filter was used. The contrast can be "put back" but then some colours start to appear. Purple fringes show more strongly in the "no filter" image, but that may just be because they're better defined.

Towards the middle the sharpness is OK, so I think if the filter were needed then there wouldn't be much lost, there.
thank you ChrisR for taking the time to evaluate results! :D I appreciate your considered opinión. Will continue tests as more filters and or spacer rings are available.

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Post by Carmen »

rjlittlefield wrote:Just checking... Did you have the 100 mm set on or very near to infinity focus? Using an infinity objective, if the rear lens is set far from infinity, things can get weird. I am a little concerned about things being differently weird in the two different cases, due to focusing issues.

--Rik
Thank you Rik for following this issue. The macro lens initially was set to infinity. To course focus, the entire camera-lens combination is CAREFULLY moved along the perpendicular axis; fine focus was achieved vía Canon's EOS utility software on humble note-book computer (finally resting close to infinity).

On the following day, I noticed the target had moved between the two test photo's. I probably touched it when adding filter. Next time I must secure the sand paper taget!

I plan more tests as additional filters and spacer rings become available. This should give a better idea of optimal position of micro' objective in relation to macro lens, effect of in-line filters, etc...

p.s. brilliant explanation of halo effect and limitations of focus stacking software! :D THANK YOU Rik!

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Re: Nikon CFi 4x Plan Achromat on Canon 100mm f/2.8L Macro I

Post by hugodang »

I would like to tell you I’m very like what you do, especially explains how you do, and you show pictures with details, so I would like talk with you about EOS Utiliti’s.( above I wrote without translation).
Firstly I must to say after reading this topis = http://www.photomacrography.net/forum/v ... s+utilitys
because of that I am equipped Canon EOS 60D and CANON 100 mm MACRO f/2.8 USM, (with IS is much more expensive price)
with this combo I made some test with : Canon EOS Utiliti’s, Heicon remote, digicamcontrol , I show you after .

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Re: Nikon CFi 4x Plan Achromat on Canon 100mm f/2.8L Macro I

Post by Carmen »

hugodang wrote:I would like to tell you I’m very like what you do, especially explains how you do, and you show pictures with details, so I would like talk with you about EOS Utiliti’s. . . I made some test with : Canon EOS Utiliti’s, Heicon remote, digicamcontrol , I show you after .
Hello hugo! :D

I would love to see your tests! I suggest you start a new thread to this end.

cheers! :D

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